The present seal structure yields a very important benefit that has eluded other persons skilled in the art. It can be retrofitted to existing, worn machinery to enhance the protection of costly lubricated machine components. This seal can replace existing seals, and the performance of this seal exceeds that of all other standard-sized, commercially available, conventional, lip and sleeve type seals. The only commercially available type of seal with performance comparable to this embodiment is the dual cone face seal. It is known by those in the art that dual cone face shields have disadvantages that significantly restrict their use. The seal disclosed here overcomes the two major inherent disadvantages of dual cone face seals--large size and high cost.
Conventional unitized lip and sleeve seals are much smaller than dual cone face seals. Since this seal can be installed as a direct replacement for ordinary seals, it can be specified and used without making any modifications to the design of an existing machine. The shaft, the bore, and the housing in which the seal operates are identical whether the present seal or conventional seals are used. Wherever dual cone face seals are desired, the machine must have been originally designed specifically for their use because they are much larger than ordinary seals. They are simply too big to fit all of the machine locations where their superior performance could justify the significant added cost.
However, the availability of a seal having the superior performance characteristics of an embodiment according to the present disclosure in a package the size of ordinary seals gives additional freedom to designers of heavy machinery and severe duty assemblies. Design possibilities made available by this new seal include increasing the size of wear surfaces without the necessity of increasing the overall size of the assembly to enhance the useful life of machines and their component parts. Another design possibility is to expand the utility of existing designs by making them better adapted for broader ranges of service.
The cost of making a seal according to the present disclosure is only a fraction of the cost of making a dual cone face seal. Cost savings can be substantial because the manufacturing cost for a dual cone face seal is currently between twenty and ninety times the cost of a conventional seal. A preferred embodiment of the present disclosure is expected to be two to three times the cost of a conventional seal. In some applications, such as crawler vehicles, a single machine will typically require 40 to 60 roller seals, each of which is subjected to extremes of heat, cold, moisture, dust, abrasives, acids and alkalis. In addition, the loads imposed on track vehicle components fluctuate extremely. For example, a roller may be subject to little load while the vehicle operates on a flat, level surface; but when tracks advance to a raised obstruction such as a rock, each roller that moves over the rock may be sequentially required to support almost the entire weight of the vehicle. The constantly fluctuating loads exacerbate the effects of any deviation from component design tolerances.
The most important benefit of the seal now disclosed is that it can create permanently lubricated shaft and bearing assemblies that can withstand severe use. This seal may enable equipment manufacturers to improve the performance of their machinery by reducing maintenance requirements. It is believed that existing vehicles and other machines can be retrofitted advantageously by replacing the original re-greasable seals with this new permanently lubricated seal. It is to be understood, however, that the present seal can be used to seal in either oil or grease and to exclude all environmental contaminants that do not attack the materials from which the seal is manufactured.
It is an object of the invention to accomplish the foregoing and to teach the structure of an externally flangeless retrofittable severe duty seal for a shaft.
It is a further object of this disclosure to show an embodiment useful for sealing bearings in shaft-mounted rotary rollers used in track-driven vehicles.
Another object is to provide an embodiment that may be useful in any application where a shaft and shaft bearing or bushing surfaces may be exposed to mud, dust, abrasives, cement, submersion, abrasive liquids or other substances that could damage relative rotary mechanical components.
Another object hereof is to disclose a seal that lasts longer than previously known low cost seals adapted for severe duty applications.
Another object of the present disclosure is to make essentially all of the important benefits of a dual cone face seal available at a much lower cost.
Yet another object hereof is to make essentially all of the important benefits of a dual cone face seal available in a physically smaller assembly.
It is an object to make essentially all of the important benefits of a dual cone face seal available in an assembly having the same physical dimensions as a conventional single lip or double lip seal.
Another object hereof is to provide an embodiment that can function as an excluder seal, as a grease seal, as an oil seal, and as a seal for other liquids at low and moderate pressures.
Another object of this disclosure is to provide a seal having a shaft-contacting sleeve that enables the seal to be installed on and to operate reliably with shafts having imperfections such as those ordinarily caused by wear and use.
Another specific object is to provide a unitary seal structure that both improves reliability, and makes seal installation easier compared to installation of seals that are composed of two or more separable parts.
A further object is to provide a seal with sealing elements that include: a main sealing lip with a garter spring that biases the main sealing lip against the outside of the sleeve, at least one dust lip that contacts the sleeve, at least one dust lip that contacts the inner surface of the housing, at least one face dust lip that contacts the inner surface of the faceplate, and an elastomeric, shaft-contacting faceplate ring.
These and further objects of the apparatus taught in accordance with this specification, the claims, and the appended drawing figures are set forth below.